According to the IAEA Safety Standard Series—Regulations for the Safe Transport of Radioactive Material 1996 Edition Regulations no. TS-R-1 (ST-1 Revised) of the International Atomic Energy Agency, Vienna (German version BfS-ET-31/00) July 2000 salt meshes are subjected to extreme degradation in the so-called Type B casks for transporting and storing highly radioactive materials.
These regulations are revised and set down in detail in English version ST-1. In general there are the following mechanical, thermal, and radiological recommendations:
Nine-meter drop test, pin-drop test, heat test, water-pressure test, as well as handling regulations and regulations regarding reporting of accidents.
According to industry-wide requirements that are based on the world-wide IAEA Regulations and that correspond to the recommendations of the accident-rectifying regulations (according to GGVS/ADR, GGVS/RID, GGVSee/JMDG) the construction of the Type B shipping elements (these are the casks with a radioactive inventory above the limit where their release does not create any increased danger) are based on mechanical, thermal, and radiological tests that ensure the safety of the casks even in severe accidents. They are thus the sole category of safety package where the safety is ensured even in the case of severe accidents.
The mechanical tests for Type B shipping elements, the standard massive heavy vessels, belongs to the nine-meter drop sequence onto a rigid floor and a one-meter drop onto a pin in the position in which the cask is most seriously damaged, which means that for each test there must be a number of drops so that the worst damage for the various parts of the cask can be assessed for each drop. The thermal test following the drop test is a 30-minute burn with complete flame envelopment of the cask by an open fuel-oil flame which heats the entire cask to at least 800° C. These tests set by the IAEA regulations simulate “real” accident situations (prior to 11 Sep. 2001) and have quite a margin of safety.
In mechanical tests it is very important that the cask be dropped on an unyielding floor as this rigidity is not really encountered in real accidents. Since the cask mass is multiplied by the impact deceleration to produce the actual impact force, a nine-meter drop onto a rigid floor produces an impact force that is much higher than that reached in reality on impacting at a much higher speed on a softer floor. This determination as well as the fact that in particular Type B cask that are used for the shipping of spent fuel elements and highly radioactive waste as a result of their massive construction have much greater safety in severe accidents as can be determined by a number of tests.
In addition the Type B cask must comply with radiological requirements. These requirements are also spelled out in ST-1.
Furthermore the container system can be used without this ion shielding for example for other dangerous materials.
What is more, it is essential to take into account what will happen when traveling by train, truck, or boat. Even the analysis of accidents must be done according to the requirements of the IAEA and country-specific requirements.
The known so-called Castor casks do not comply in various ways to the requirements of the IAEA and the applicable German requirements regarding transport and storage.
This type of cask is made by machining as a monolithic object cut from a monolithic block of spherical-graphite cast iron and is provided with separate bores and with machined cooling ribs and are provided to hold spent fuel elements in water in storage pools (wet storage) in which the fuel elements are maintained cool (at least 5 years).
Thus the complete machined but monolithic and thick-walled cask blocks weighing between 100 and 150 t and holding spent fuel elements are completely submerged. The normally brittle surface of the mechanically machined anthracite casting must be given some surface treatment.
Here in the contaminated storage-pool water the spherical-graphite block cask is contaminated inside and outside. As a result it is necessary to meticulously decontaminate the exterior (1998 was the start of a complete handling ban from outside contamination).
The required IAEA drop tests cannot be done with an empty cask. The selected spherical-graphite material does not resist such forces created by mass times acceleration without bursting because of the brittle nature of the material. Trials cannot be made according to the necessary regulations either by calculation (with a substantial margin for error). The actual results can be calculated with models provided with shock absorbers and actually done with Pollux and the so-called Japanese Castor casks.
This testing of the Pollux and Japanese Castor casks, which are provided with large top and bottom shock absorbers only gives results that relate to the shock absorbers and not to the actual strength of the casks.
This results in the following rule: Castor casks with top and bottom shock absorbers must be integrated into form Type B container systems.
The actual spherical-graphite cask is never actually tested. Even the flame test, with 800° C. for at least 30 minutes, is not done. To date there is no reliable data.